Pneumatic vehicle tire

ABSTRACT

A pneumatic vehicle Eire having a tread with at least one profile block row ( 2, 3 ) which is divided into a multiplicity of profile blocks ( 2   a,    3   a ) by transverse channels ( 6, 7 ) having channel flanks ( 7   a ) which extend at an angle (α, β) of up to 50° with respect to the axial direction, wherein transverse channels ( 6, 7 ) are provided, in each of which there is formed a base elevation ( 8, 8   I ) which locally reduces the depth (t 1 ) of the transverse channel ( 6, 7 ) and which connects successive profile blocks ( 2   a,    3   a ) in circumferential direction to one another, wherein the base elevation ( 8, 8   I ) has at least two base elevation parts ( 8   a,    8   b,    8   c ) of different height (h max, a , h max, bc ). 
     Centrally on each of the base elevation parts ( 8   a,    8   b,    8   c ), there is formed at least one groove ( 10, 11 ) which runs in the dire tion of extent of the transverse channel ( 6, 7 ) and which emerges from the base elevation part ( 8   a,    8   b,    8   c ) at least on one side.

The invention relates to a pneumatic vehicle tire having a tread with at least one profile block row which is divided into a multiplicity of profile blocks by transverse channels having channel flanks which extend at an angle of up to 50° with respect to the axial direction, wherein transverse channels are provided, in each of which there is formed a base elevation which locally reduces the depth of the transverse channel and which connects successive profile blocks in a circumferential direction to one another, wherein the base elevation has at least two base elevation parts of different height.

Such a pneumatic vehicle tire is known for example from EP 1 974 957 A1. The tread of the tire has at least one profile block row with transverse channels, in each of which a base elevation is formed. The base elevation is composed of at least two base elevation parts of different heights, wherein, in particular, up to ten base elevation parts of different heights are provided. During travel on soft underlying surfaces, the different heights of the base elevation parts are intended to allow grip behavior that is adapted to the amount of mud, snow or slush on the surface.

The invention is based on the object, in the case of a pneumatic vehicle tire of the type mentioned in the introduction, of improving the driving characteristics on snowy roads, in particular the so-called snow-on-snow friction, wherein it is sought to ensure good grip characteristics under traction in the circumferential and transverse directions.

The stated object is achieved according to the invention in that, centrally on each of the base elevation parts, there is formed at least one groove which runs in the direction of extent of the transverse channel and which emerges from the base elevation part at least on one side.

When driving on snow or slush, snow is pressed and compacted into the grooves on the base elevation parts, as a result of which particularly good traction characteristics in the circumferential and transverse directions can be achieved owing to a pronounced effect of snow-on-snow friction. Owing to the at least two base elevation parts of different heights, this effect can be maintained effectively over the service life of the tire or with progressive tread wear.

According to one preferred embodiment, in at least one of the base elevation parts, the groove extends all the way through the base elevation part. A greater amount of snow can accumulate in a groove that extends all the way through than in a groove that does not extend all the way through, which has a particularly advantageous effect on the effect of snow-on-snow friction.

In this embodiment, it is preferred if, at least in the base elevation part(s) with the smaller height, the groove extends all the way through the base elevation part. This measure is particularly advantageous for good snow-on-snow friction with progressive tread wear.

According to a further preferred embodiment, the base elevation part with the greater height is provided with two grooves which emerge on different sides and which run in particular in alignment with one another. Snow is compacted particularly effectively in blind grooves of this type, which act as “snow pockets”.

In this embodiment, it is furthermore preferred if the grooves which emerge on different sides of the base elevation part have a length, projected into the axial direction, of 20% to 40%, in particular of at least 30%, of the length, projected into the axial direction, of the base elevation part.

According to a further preferred embodiment, the grooves have, in a radial direction, a depth of 0.5 mm to 3.0 mm, in particular of up to 2.0 mm, and a width of 35% to 50%, in particular of at least 40%, of the width of the associated transverse channel. This measure also supports good traction characteristics in the circumferential and transverse directions owing to the effect of snow-on-snow friction.

The effects described are particularly effectively maintained with increasing wear of the tread if the heights of the base elevation parts are adapted to one another in a specific way. In this regard, it is advantageous if the height of the base elevation part with the greater height is 40% to 100%, in particular 45% to 85%, and particularly preferably at least 50%, of the depth of the associated transverse channel, and if the height of the base elevation part with the smaller height is 20% to 30%, in particular 23% to 27%, of the depth of the associated transverse channel.

According to a further preferred embodiment, the base elevation part with the smaller height is provided with a depression which adjoins the base elevation part with the greater height and which extends to the channel flanks and which has a width of 0.7 mm to 3.0 mm, in particular of 1.0 mm to 2.0 mm, and a depth of 0.3 mm to 2.0 mm, in particular of 0.5 mm to 1.0 mm. These grooves act as additional snow pockets and provide additional grip edges.

In a further preferred embodiment, on at least one side, in particular on each side, of the base elevation, a depression with a width of 0.7 mm to 3.0 mm, in particular of 1.0 mm to 2.0 mm, and a depth of 0.3 mm to 2.0 mm, in particular of 0.5 mm to 1.0 mm, is formed on the channel base of the transverse channel. This, too, is a measure for improving snow grip.

In a particularly preferred embodiment, base elevations are provided which are each composed of two or three base elevation parts of different heights, wherein, in the case of three base elevation parts, the middle base elevation part is the tallest.

In this embodiment, it is advantageous if the base elevations with exactly two base elevation parts are formed in a transverse channel of a middle profile block row, and if the base elevations with exactly three base elevation parts are formed in a transverse channel of a shoulder-side profile block row.

The base elevation parts are preferably each delimited in a radial direction by a top surface which, in the regions that are free from grooves, runs parallel to the tread periphery. This measure promotes the accumulation of snow in the grooves of the base elevation parts.

The base elevation preferably has a length, projected into the axial direction, of 30% to 50%, in particular of 25% to 40%, of the length, projected into the axial direction, of the transverse channel.

In further preferred embodiments, on the channel base of the transverse channel, there is formed a channel base channel which is narrower than the transverse channel and which has a depth of 15% to 25% of the depth of the transverse channel and a width of 40% to 60% of the width of the transverse channel, such that further grip edges are available.

Further features, advantages and details of the invention will now be described in more detail with reference to the drawing, which schematically shows an exemplary embodiment of the invention. In the drawing:

FIG. 1 shows a plan view of a partial development of a tread of a pneumatic vehicle tire with a design variant according to the invention,

FIG. 2 shows an enlarged plan view of the detail Z₂ in FIG. 1 ,

FIG. 3 shows a section along the line III-III in FIG. 2 ,

FIG. 4 shows a section along the line IV-IV in FIG. 2 ,

FIG. 5 shows a section along the line V-V in FIG. 2 , and

FIG. 6 shows a section along the line VI-VI in FIG. 2 .

Pneumatic vehicle tires designed according to the invention are, in particular, tires of radial type of construction for passenger motor vehicles, vans or light trucks, wherein the tires are provided for driving under wintry driving conditions.

FIG. 1 shows a circumferential portion of a tread 1 of a pneumatic vehicle tire. In the exemplary embodiment shown, the tread 1 has a profiling of directional design, wherein the pneumatic vehicle tire must be installed on the vehicle so as to have the rolling direction symbolized by the arrow R during forward travel. The equatorial plane of the tire is indicated by a dashed line A-A, and the lateral edges of the ground-contacting part of the tread (corresponds to the statically determined footprint according to E.T.R.T.O. standards: load at 70% of the maximum load-bearing capacity at an internal pressure of 85% according to the E.T.R.T.O. standard) are indicated by dashed lines 1.

In each tread half, the tread 1 has a middle profile block row 2 and a shoulder-side profile block row 3. The middle profile block rows 2 are separated from one another by a central circumferential channel 4 which is straight in plan view and which runs along the equatorial plane, and from the respectively adjacent shoulder-side profile block row 3 by a shoulder-side circumferential channel 5, which in the exemplary embodiment shown runs in a straight manner in plan view. The circumferential channels 4, 5 are formed to the respectively provided profile depth T₁ (indicated in FIG. 6 ), which is typically 6.5 mm to 10.0 mm for the preferred tire type.

Each central profile block row 2 is provided with middle transverse channels 6 running parallel to one another, and each shoulder-side profile block row 3 is provided with shoulder-side transverse channels 7 running parallel to one another, wherein the transverse channels 6, 7 extend in a V-shape across the tread width. The middle transverse channels 6 divide the middle rows of profile blocks 2 into middle profile blocks 2 a and run in slightly curved form and at an angle α of 30° to 55°, in particular of at least 45°, with respect to the axial direction. The shoulder-side transverse channels 7 divide the shoulder-side profile block rows 3 into shoulder-side profile blocks 3 a and likewise run in slightly curved form and at an angle β of 5° to 20° with respect to the axial direction. The angles α and β of the transverse channels 6, 7 each relate to a centerline m_(QR) which follows the channel profile and which is therefore curved (shown in FIG. 2 for one transverse channel 7) and are measured relative to a local tangent to the centerline m_(QR).

A base elevation 8 is formed within the ground contact patch in each shoulder-side transverse channel 7, and a base elevation 8 ^(I) is formed in each middle transverse channel 6, wherein the base elevations 8, 8 ^(I) connect the respective profile blocks 2 a, 3 a to one another and thus locally reduce the depth of the transverse channel 6, 7. The further configuration of a shoulder-side transverse channel 7 and of a base elevation 8 will be discussed in more detail below with reference to FIG. 2 and the associated sections in FIG. 3 to FIG. 6 . The differences between the base elevation 8 ^(I) and the base elevation 8 will then be discussed.

According to FIG. 2 and FIG. 3 , the shoulder-side transverse channel 7 has two channel flanks 7 a and, in the region outside the base elevation 8, a channel base 7 b with a U-shaped cross section (FIG. 3 ). The transverse channel 7 has, at the tread periphery, a width b₁ of 5.0 mm to 8.0 mm measured perpendicularly to its centerline m_(QR), has, in the region of the channel base 7 b, a maximum depth t₁ (FIG. 3 , FIG. 6 ) measured in a radial direction, and has, measured within the ground contact patch and based on the centerline m_(QR), a length l₁ projected into the axial direction. The maximum depth t₁ of the transverse channel 7 is 0.5 mm to 2.0 mm less than the profile depth T₁(FIG. 3 , FIG. 6 ).

According to FIG. 3 , as viewed in cross section of the transverse channel 7, the channel flanks 7 a run at an angle γ of 0° to 7°, in particular of 1.5° to 6°, with respect to the radial direction, wherein the angles γ of the two channel flanks 7 a correspond or differ from one another, and wherein the channel flanks 7 a may have chamfers, rounded portions or the like, in particular of known design, running to the tread periphery, wherein these are not taken into consideration in the measurement of the width b₁ of the transverse channel 7. At the channel base 7 b, there is formed a channel base channel 7 c which is designed to be narrower than the transverse channel 7 and which is U-shaped as viewed in the cross section of the transverse channel 7, wherein oblique or rounded transition flanks 7 d which slope downward to the channel base channel 7 c run between the channel flanks 7 a and the channel base 7 b. The channel base channel 7 c has, in the radial direction, a depth t₁′ of 15% to 25% of the depth t₁ and, at the radially outer end of its U-limbs, a width b₁′ of 40% to 60% of the width b₁ of the transverse channel 7, and, owing to the base elevation 8, is divided into a channel base channel section 7 c′ at the inside of the tread and a channel base channel section 7 c″ at the outside of the tread (FIG. 2 ).

According to FIG. 2 , the base elevation 8 is composed of a base elevation part 8 a, a lateral base elevation part 8 b at the outside of the tread, and a lateral base elevation part 8 c at the inside of the tread. At each side of the base elevation 8, there is situated a depression 9 which adjoins the respective lateral base elevation part 8 b, 8 c and which is formed on the channel base 7 b and at which the channel base channel section 7 c′ at the inside of the tread or the channel base channel section 7 c″ at the tread outside ends. As shown in FIG. 6 , the depressions 9, as viewed in longitudinal section of the transverse channel 7, are U-shaped and have a width b_(V1) of 0.7 mm to 3.0 mm, in particular of 1.0 mm to 2.0 mm, a depth t_(V1) of 0.3 mm to 2.0 mm, in particular of 0.5 mm to 1.0 mm, and preferably a radial spacing a₁ of 1.0 mm to 2.0 mm to the level of the profile depth T₁.

As is also shown in FIG. 2 , the base elevation 8 has, measured at its base and based on the centerline m_(QR), a length l₂, projected into the axial direction, of 30% to 50%, in particular of 35% to 45%, of the length l₁, projected into the axial direction, of the transverse channel 7. The base elevation part 8 a has a length l_(a), the lateral base elevation part 8 b has a length l_(b) and the lateral base elevation part 8 c has a length l_(c), wherein the lengths l_(a), l_(b), l_(c) are measured analogously to the length l₁ of the transverse channel 7. The length l_(a) of the base elevation part 8 a and the length l_(b) of the lateral base elevation part 8 b is in each case 33% to 45% of the length l₁ of the transverse channel 7, and, in the exemplary embodiment shown, the length l_(c) of the lateral base elevation part 8 c is smaller than the length l_(a), l_(b). The base elevation 8 has, based on the centerline m_(QR), a spacing a₂, projected into the axial direction, of 2.0 to 3.0 mm to the respective shoulder-side circumferential channel 5.

According to FIG. 6 , the base elevation part 8 a is cuboidal and, in relation to the level of the channel base 7 b (=depth t₁), has a maximum height h_(max, a), measured in a radial direction, of 40% to 100%, in particular of 45% to 85%, and particularly preferably of at least 50%, of the depth t₁. The base elevation part 8 a is delimited in a radial direction by a top surface 8 a′ and also by two side surfaces 8 a″ running in a radial direction. Two grooves 10 are formed on the top surface 8 a′, which grooves proceed from the different side surfaces 8 a″, are in alignment with one another, are spaced apart correspondingly from the channel flanks 7 a, and are separated by a web (FIG. 2 ). The grooves 10 give rise to an H shape of the top surface 8 a′ as seen in plan view and in the direction of extent of the transverse channel 7 (FIG. 2 ), wherein the top surface 8 a′ is oriented parallel to the tread periphery in the regions that are free from grooves 10. As shown in FIG. 5 , as viewed in cross section of the transverse channel 7, the grooves 10 are U-shaped and have a width b_(N1) of 35% to 50%, in particular at least 40%, of the width b₁ of the transverse channels 7, a depth t_(N1), measured in the radial direction, of 0.5 mm to 3.0 mm, in particular up to 2.0 mm, and a length l_(N1) (FIG. 2 ), projected into the axial direction, of 20% to 40%, in particular of at least 30%, of the length l_(a)(FIG. 2 ) of the base elevation part 8 a.

According to FIG. 6 , the lateral base elevation parts 8 b, 8 c have a maximum height h_(max, bc) relative to the level of the channel base 7 b of 20% to 30%, in particular of 23% to 27%, of the depth t₁. As shown in FIG. 2 , centrally on each of the base elevation parts 8 b, 8 c, there is formed a groove 11 (FIG. 5 ) which has a U-shaped cross section and which is correspondingly spaced apart from the channel flanks 7 a and which extends all the way through the respective base elevation part 8 b, 8 c in the direction of extent of the transverse channel 7 and which has a width b_(N2) (FIG. 4 ) of 35% to 50% of the width b₁ of the transverse channel 7 and a depth t_(N2) (FIG. 4 ) in a radial direction of 0.5 mm to 3.0 mm, in particular of up to 2.0 mm. As shown in FIG. 6 , the lateral base elevation parts 8 b, 8 c in the exemplary embodiment shown are provided with a depression 12 adjoining the middle base elevation part 8 a, the cross section, width and depth of which depression 12 correspond to those of the depression 9, and which depression 12 extends between the channel flanks 7 a and therefore between the shoulder-side profile blocks 3 a.

The base elevation 8 ^(I) already mentioned, which is shown in FIG. 1 and which is provided in each case in a middle transverse channel 6, is a variant of the base elevation 8. Said base elevation 8 ^(I) differs from this in particular in that it is composed of only two base elevation parts, one of which is designed analogously to the middle base elevation part 8 a and the other of which is designed analogously to the lateral base elevation part 8 b. In the exemplary embodiment shown, each base elevation 8 ^(I) has a smaller spacing to the central circumferential channel 4 than to the respective shoulder-side circumferential channel 5.

Furthermore, in the exemplary embodiment shown, at some corner regions of the profile blocks 2 a, 3 a, there are formed sloping corner chamfers (not designated in FIG. 1 and FIG. 2 ) which are designed in particular in a known manner and are not part of the invention.

The invention is not limited to the exemplary embodiments described.

For example, the base elevation part 8 a may have only one of the grooves 10. The depressions 9, 12, and the channel base channel 7 c running in the region outside the base elevation 8, 8 ^(I), are optional. The tire has at least one profile block row with transverse channels comprising base elevations.

LIST OF REFERENCE SIGNS

-   1 . . . Tread -   2 . . . Middle profile block row -   2 a . . . Middle profile block -   3 . . . Shoulder-side profile block row -   3 a . . . Shoulder-side profile block -   4 . . . Central circumferential channel -   5 . . . Shoulder-side circumferential channel -   6 . . . Middle transverse channel -   7 . . . Shoulder-side transverse channel -   7 a . . . Channel flank -   7 b . . . Channel base -   7 c . . . Channel base channel -   7 c′, 7 c″ . . . Channel base channel section -   7 d . . . Transition flank -   8, 8 ^(I) . . . Base elevation -   8 a . . . Base elevation part -   8 a′ . . . Top surface -   8 a″ . . . Side surface -   8 b . . . Lateral base elevation part -   8 c . . . Lateral base elevation part -   9 . . . Depression -   10, 11 . . . Groove -   12 . . . Depression -   A-A . . . Line (equatorial plane) -   a₁, a₂ . . . Spacing -   b₁, b₁′, b_(V1), b_(N1), b_(N2) Width -   h_(max, a), h_(max, bc). Maximum height -   l₁, l₂, l_(a), l_(b), l_(c), l_(N1) Length -   l . . . Line (lateral edge of the ground contact patch) -   m_(QR) . . . Centerline -   R . . . Arrow (rolling direction) -   T₁ . . . Profile depth -   t₁ . . . Maximum depth -   t₁′, t_(V1), t_(N1), t_(N2) Depth -   α, β, γ . . . Angles 

1.-15. (canceled)
 16. A pneumatic vehicle tire comprising a tread with at least one profile block row (2, 3) which is divided into a multiplicity of profile blocks (2 a, 3 a) by transverse channels (6, 7) having channel flanks (7 a) which extend at an angle (α, β) of up to 50° with respect to an axial direction, wherein the transverse channels (6, 7) are provided, in each of which there is formed a base elevation (8, 8 ^(I)) which locally reduces a depth (t₁) of the transverse channels (6, 7) and which connects successive profile blocks (2 a, 3 a) in a circumferential direction to one another, wherein the base elevation (8, 8 ^(I)) has at least two base elevation parts (8 a, 8 b, 8 c) of different heights (h_(max, a), h_(max, bc)); and, wherein centrally on each of the at least two base elevation parts (8 a, 8 b, 8 c), there is formed at least one groove (10, 11) which runs in the direction of extent of the transverse channels (6, 7) and which emerges from each of the at least two base elevation parts (8 a, 8 b, 8 c) at least on one side.
 17. The pneumatic vehicle tire as claimed in claim 16, wherein in a first base elevation part of the at least two base elevation parts (8 b, 8 c), a first groove (11) of the at least one groove extends all the way through the first base elevation part (8 b, 8 c).
 18. The pneumatic vehicle tire as claimed in claim 17, wherein in a base elevation part (8 b, 8 c) with a smallest height (h_(max, bc)) of the at least two base elevation parts, the first groove (11) extends all the way through the base elevation part (8 b, 8 c) with the smallest height (h_(max, bc)).
 19. The pneumatic vehicle tire as claimed in claim 16, wherein a base elevation part (8 a) with a greatest height (h_(max, a)) of the at least two base elevation parts is provided with two grooves (10) which emerge on different sides and which run in alignment with one another.
 20. The pneumatic vehicle tire as claimed in claim 19, wherein the two grooves (10) which emerge on different sides of the base elevation part with the greatest height (8 a) have a length (l_(N1)), projected into the axial direction, of 20% to 40%, of a length (l_(a)), projected into the axial direction, of the base elevation part (8 a) with the greatest height.
 21. The pneumatic vehicle tire as claimed in claim 19, wherein the two grooves (10) which emerge on different sides of the base elevation part with the greatest height (8 a) have a length (l_(N1)), projected into the axial direction, of at least 30%, of a length (l_(a)), projected into the axial direction, of the base elevation part (8 a) with the greatest height.
 22. The pneumatic vehicle tire as claimed in claim 16, wherein the at least one groove (10, 11) has, in a radial direction, a depth (t_(N1), t_(N2)) of 0.5 mm to 3.0 mm, and a width (b_(N1), b_(N2)) of 35% to 50%, of a width (b₁) of an associated transverse channel of the transverse channels (6, 7).
 23. The pneumatic vehicle tire as claimed in claim 16, wherein the at least one groove (10, 11) has, in a radial direction, a depth (t_(N1), t_(N2)) of up to 2.0 mm, and a width (b_(N1), b_(N2)) of at least 40%, of a width (b₁) of an associated transverse channel of the transverse channels (6, 7).
 24. The pneumatic vehicle tire as claimed in claim 16, wherein a base elevation part (8 a) with a greatest height (h_(max, a)) of the at least two base elevation parts has a height (h_(max, a)) of from 40% to 100% of a depth (t₁) of an associated transverse channel of the transverse channels (6, 7), and wherein a height (h_(max, bc)) of a base elevation part with a smaller height (h_(max, bc)) of the at least two base elevation parts is 20% to 30% of the depth (t₁) of the associated transverse channel (6, 7).
 25. The pneumatic vehicle tire as claimed in claim 16, wherein a base elevation part (8 b, 8 c) with a smallest height (h_(max, bc)) of the at least two base elevation parts is provided with a depression (12) which adjoins a base elevation part (8 a) with a greatest height (h_(max, a)) of the at least two base elevation parts, wherein the depression extends to channel flanks (7 a), and wherein the depression has a width of 0.7 mm to 3.0 mm and a depth of 0.3 mm to 2.0 mm.
 26. The pneumatic vehicle tire as claimed in claim 25, wherein the width of the depression is from 1.0 mm to 2.0 mm, and the depth of the depression is from 0.5 mm to 1.0 mm
 27. The pneumatic vehicle tire as claimed in claim 16, wherein on each side of each base elevation (8, 8′) formed in the transverse channels (6, 7), a depression (9) with a width (b_(V1)) of 0.7 mm to 3.0 mm, and a depth (t_(V1)) of 0.3 mm to 2.0 mm, is formed on a channel base (7 b) of each of the transverse channels (6, 7).
 28. The pneumatic vehicle tire as claimed in claim 27, wherein the a width (b_(V1)) is from 1.0 mm to 2.0 mm, and the a depth (t_(V1)) is from 0.5 mm to 1.0 mm.
 29. The pneumatic vehicle tire as claimed in claim 16, wherein at least one of each base elevation formed in the transverse channels is composed of two base elevation parts of different heights.
 30. The pneumatic vehicle tire as claimed in claim 29, wherein the at least one of each base elevation is formed in a transverse channel (6) of a middle profile block row (2).
 31. The pneumatic vehicle tire as claimed in claim 16, wherein at least one of each base elevation formed in the transverse channels is composed of three base elevation parts (8 a, 8 b, 8 c), and wherein a middle base elevation part (8 b) of the three base elevation parts is the tallest.
 32. The pneumatic vehicle tire as claimed in claim 31, wherein the at least one of each base elevation formed in the transverse channels is formed in a shoulder-side profile block row (3).
 33. The pneumatic vehicle tire as claimed in claim 16, wherein the at least two base elevation parts (8 a, 8 b, 8 c) are each delimited in a radial direction by a top surface (8 a′) which, in the regions that are free from the at least one groove (10, 11), runs parallel to the a periphery.
 34. The pneumatic vehicle tire as claimed in claim 16, wherein the base elevation (8, 8 ^(I)) has a length (l₂), projected into the axial direction, of 30% to 50% of length (l₁), projected into the axial direction, of the transverse channels (6, 7).
 35. The pneumatic vehicle tire as claimed in claim 16, wherein on a channel base (7 b) of each of the transverse channels (6, 7), there is formed a channel base channel (7 c) which is narrower than the transverse channels (6, 7) and which has a depth (t₁′) of 15% to 25% of a depth (t₁) of the transverse channels (7) and a width (b₁′) of 40% to 60% of a width (b₁) of the transverse channels (7). 